SCIENCE MADE FUN !

Cas Elektrik Statik ( Bab 7 Tingkatan 3 )

Struktur atom

Struktur atom.

• Atom mengandungi zarah proton, neutron dan elektron. Proton dan neutron membentuk nukleus atom, manakala elektron pula bergerak mengelilingi nukleus (nucleus).
• Proton dan elektron mempunyai cas elektrik, manakala neutron tidak mempunyai cas elektrik.
• Proton bercas positif (+) dan elektron bercas negatif (-).
• Atom mengandungi jumlah proton dan elektron yang sama, menjadikan ianya seimbang. Oleh itu, suatu atom itu tidak mempunyai cas elektrik.
  
  

Suatu atom itu akan mempunyai cas apabila terdapat pemindahan elektron.

• Suatu objek itu adalah neutral jika atomnya mempunyai jumlah proton yang sama dengan elektron.
• Suatu objek itu bercas positif jika atomnya mempunyai jumlah proton yang melebihi jumlah elektron.
• Suatu objek itu bercas negatif jika atomnya mempunyai jumlah elektron yang melebihi jumlah proton.

Pemindahan elektron menyebabkan dua jenis fenomena elektrik:

1. Elektrik statik (static electricity), fenomena dimana cas adalah statik/tidak bergerak.
2. Arus elektrik (current electricity), fenomena dimana cas adalah bergerak.
   Elektrostatik (electrostatics) adalah kajian mengenai cas elektrik statik atau cas elektrik pada keadaan rehat (tidak bergerak).

THE END……good luck

Mineral Yang Terdapat Di Dalam Kerak Bumi ( Bab 6 Tingkatan 3 )

Mineral adalah unsur semulajadi (natural element) atau sebatian (compound) yang terdapat di dalam kerak Bumi (Earth's crust).

Mineral mempunyai komposisi dan struktur kristal tertentu. Contoh-contoh mineral adalah calcite, feldspar, kuarza (quartz), mika (mica), marmar (marble) dan silikat (silicate).

Hanya unsur yang tidak aktif sahaja boleh wujud secara bebas dalam kerak Bumi. Sementara itu, unsur-unsur aktif akan bertindak balas dengan unsur-unsur lain bagi membentuk sebatian tertentu.

Unsur-unsur semula jadi yang biasanya ditemui di dalam kerak Bumi adalah emas (gold), perak (silver), platinum, raksa (mercury) dan arsenik (arsenic).

Jadual di bawah menunjukkan peratusan unsur-unsur mineral yang terdapat dalam kerak Bumi.

Unsur	% mengikut berat
Oksigen	46.6
Silikon	27.7
Aluminium	8.1
Besi / Ferum	5.0
Kalsium	3.6
Sodium	2.8
Potassium	2.6
Magnesium	2.1
Titanium	0.4
Hidrogen / Karbon	0.14

Peratusan unsur di dalam kerak bumi.

Hampir 75% daripada berat mineral di dalam kerak Bumi adalah terdiri daripada unsur-unsur oksigen dan silikon. Oleh itu, mineral silikat (silicate minerals) yang mengandungi oksigen dan unsur-unsur silikon membentuk jumlah yang terbesar. Contoh mineral silikat adalah termasuk kuarza, feldspar, mika dan tanah liat.

Mineral yang tidak mengandungi unsur silikon dikenali sebagai mineral bukan silikat (non-silicate minerals). Contoh mineral bukan silikat adalah calcite, dolomit (dolomite), magnetit (magnetite) dan bijih besi (hematite).

Unsur-unsur bukan logam yang lain seperti oksigen, sulfur dan karbon biasanya wujud dalam bentuk sebatian seperti oksida (oxides), sulfida (sulphides) dankarbonat (carbonates).

Unsur-unsur yang kurang aktif bergabung dengan oksigen dan sulfur untuk membentuk oksida dan sulfida seperti oksida besi, aluminium oksida, plumbum sulfida dan besi sulfida.

Sulfida bertindak balas dengan oksigen untuk membentuk sulfat. Sebaliknya, oksida akan bertukar ke karbonat apabila bertindak balas dengan air dan karbon dioksida.

Oksida logam (metal oxide) adalah sebatian yang mengandungi logam dan oksigen.

Jadual di bawah menunjukkan beberapa contoh sebatian mineral yang ditemui di dalam kerak Bumi.

Jenis mineral	Contoh	Nama kimia	Unsur
Oksida (oxide)	Bauksit (bauxite)	Aluminium oksida	Aluminium dan oksigen
	Hematit (hematite)	Besi oksida	Besi dan oksigen
	Magnetit (magnetite)	Magnesium oksida	Magnesium dan oksigen
	Cassiterite	Timah oksida	Timah dan oksigen
Sulfida (sulphide)	Galena	Plumbum sulfida	Plumbum dan sulfur
	Pirit (pyrite)	Besi sulfida	Besi dan sulfur
	Chalcocite	Kuprum sulfida	Kuprum dan sulfur
	Blende	Zink sulfida	Zink dan sulfur
Karbonat (carbonate)	Marmar (calcite)	Kalsium karbonat	Kalsium, karbon dan oksigen
	Magnesit (magnesite)	Magnesium karbonat	Magnesium, karbon dan oksigen
	Dolomit (dolomite)	Magnesium karbonat	Magnesium, karbon dan oksigen
	Malachite	Kuprum karbonat	Kuprum, karbon dan oksigen

Contoh sebatian mineral yang ditemui di dalam kerak Bumi.

Mineral yang berlainan mempunyai ciri-ciri yang berbeza. Mineral memiliki ciri-ciri yang berbeza dari segi:

1. Kekerasan (hardness).
2. Keterlarutan dalam air (solubility in water).
3. Reaksi kepada haba dan kesannya (reaction to heat and its effect).

1. Kuarza dan calcite adalah mineral Bumi yang biasa ditemui 
   di dalam batu-batan di seluruh dunia.
   
   
   
   THE END……good luck

Corak Pertumbuhan Manusia ( Bab 5 Tingkatan 3 )

Pertumbuhan (growth) adalah satu proses yang dialami di dalam semua organisma hidup.

Proses pertumbuhan adalah melibatkan:

1. Peningkatan saiz (pembesaran) organisma.
2. Perubahan penampilan / rupa organisma.
3. Peningkatan dalam bilangan sel-sel.
4. Pembangunan fungsi organ organisma.

Pertumbuhan Manusia

Pertumbuhan / tumbesaran manusia boleh diukur dengan dua cara, iaitu melalui:

1. Ketinggian badan (body height)
2. Berat badan (body weight)

Proses pertumbuhan manusia boleh dibahagikan kepada beberapa peringkat. Pada setiap peringkat, akan terdapat perubahan dari segi bentuk, saiz dan rupa.

Secara umumnya, terdapat lima peringkat kehidupan pada manusia:

1. Peringkat awal (infancy)
2. Zaman kanak-kanak (childhood)
3. Remaja (adolescence)
4. Dewasa (adulthood)
5. Usia tua (old age)

Lima peringkat kehidupan manusia ini, boleh dipaparkan melalui lengkung pertumbuhan (growth curve). Lengkung pertumbuhan ini adalah berbentuk S (S-shaped) atau sigmoid.

Lengkung pertumbuhan manusia.

Berdasarkan rajah di atas, tumbesaran manusia terbahagi kepada peringkat berikut:

1. Peringkat awal (peringkat I). 
   Peringkat awal adalah dari umur 0 - 1 tahun. Kadar pertumbuhan pada peringkat ini adalah cepat.
   
   
2. Zaman kanak-kanak (peringkat II). 
   Peringkat zaman kanak-kanak adalah dari umur 1 - 12 tahun. Kadar pertumbuhan pada peringkat ini adalah perlahan sehinggalah remaja.
   
   
3. Remaja (peringkat III). 
   Peringkat remaja adalah dari umur 12 - 20 tahun. Kadar pertumbuhan pada peringkat ini terdapat sedikit peningkatan.
   
   
4. Dewasa (peringkat IV). 
   Kadar pertumbuhan pada peringkat ini adalah malar (constant) atau sifar. Ini bermakna bahawa pertumbuhan/tumbesaran manusia telah berhenti. Walau bagaimanapun, terdapat bahagian yang tumbuh sepanjang hayat, iaitu kulit, kuku dan rambut.
   
   
5. Usia tua (peringkat V). 
   Pada peringkat ini, kadar pertumbuhan adalah negatif dan saiz tubuh manusia juga mula mengurang. Peringkat ini berakhir dengan kematian.
   
   Walaupun lengkung pertumbuhan (growth curve) manusia secara umumnya adalah sigmoid, tetapi terdapat perbezaan dalam pertumbuhan pada lelaki dan wanita.

Lengkung pertumbuhan lelaki dan perempuan.

Berdasarkan lengkung pertumbuhan lelaki dan perempuan/wanita di atas;

• Kadar pertumbuhan budak lelaki adalah sama seperti budak perempuansemasa peringkat awal (bayi).
• Walau bagaimanapun, kadar pertumbuhan budak lelaki adalah melebihi budak perempuan semasa zaman kanak-kanak.
• Antara umur 12-14 tahun, kadar pertumbuhan adalah dilebihi oleh budak perempuan. Ini adalah kerana seorang budak perempuan mencapai akil baligh (puberty) pada usia yang lebih awal (kira-kira 12 tahun) dan zaman remajanya juga berakhir awal (kira-kira 16 tahun).
• Seorang budak lelaki mencapai akil baligh pada usia lewat sedikit(kira-kira 14 tahun) dan zaman remajanya pula berakhir pada umur kira-kira 18 tahun. Jadi, ketinggian perempuan adalah melebihi lelaki pada peringkat remaja.
• Disebabkan tempoh pertumbuhan seorang lelaki adalah lebih panjang, jadi ketinggian seorang lelaki melebihi seorang perempuan, adalah pada umur 18 tahun dan ke atas.

Zaman kanak-kanak (chilhood) adalah peringkat yang paling penting dalam pertumbuhan manusia. Jadi, kanak-kanak mestilah diberi:

1. Diet yang seimbang kerana nutrien seperti karbohidrat, protein, lemak, vitamin dan garam mineral boleh memastikan pertumbuhan yang sihat dan mencegah pelbagai penyakit kekurangan seperti marasmus (lemah seluruh badan), riket, kwashiorkor dan beri-beri.
2. Bimbingan, perlindungan, kasih sayang dan pendidikan bagi memastikan pertumbuhan rohani yang sempurna.

THE END……good luck

REPRODUCTION ( Bab 4 Tingkatan 3 )

SEXUAL AND ASEXUAL REPRODUCTION

1. Reproduction.
a. Reproduction is a process of generating offspring.
b. Reproduction is a biological process that occurs in all living organisms.
2. Importance of reproduction
a. Reproduction is important for the survival of all living organisms.
b. Reproduction is also important in maintaining continuity of organisms.
Without a mechanism for reproduction, life would come to an end.
3. There are two types of reproduction, sexual and asexual reproduction.

SEXUAL REPRODUCTION

1. Sexual reproduction involves the joining of a male and a female sex cell.
2. Fertilisation:
i. Fertilisation happens when male and female sex cells are physically
joined together.
ii. Fertilisation that happens inside a female’s body is called the internal
fertilisation.
iii. Fertilisation that happens outside a female’s body is called the external
fertilisation
3. Organisms that reproduce sexually are human beings, mammals, reptiles, fish,
birds, insects and some flowering plants.

ASEXUAL REPRODUCTION

1. Asexual reproduction does not involve the fusion of male female sex cells.
2. In asexual reproduction, a simple cell is divided by itself to produce an exact
duplicate of an organisms.
3. There are five types of asexual reproduction: PMR 03
i. binary fission – amoeba, paramecium
ii. budding - hydra
iii. spore formation - fern
iv. vegetative - grass
v. rejuvenation – starfish, flatworm, lizard
4. Organisms that reproduce asexually are:
i. paramecium
ii. hydra
iii. planarian
iv. amoeba
v. starfish
vi. some flowering and non-flowering plants
5. Binary fission:
i. Mature organisms that have reached maximum size perform cell division
to produce two daughter cells.
ii. The daughter cells produced will develop and have the same
characteristics as their parent organism.
iii. The process of binary fission begins with the division of the nucleus,
followed by the division of the cytoplasm.
iv. Examples of organisms that perform binary fission are amoeba,
paramecium and euglena (algae).
6. Rejuvenation (regeneration):
a. Rejuvenation is the replacement or regrowth of missing or injured body
part.
b. For example, if a planarian is cut horizontally, the head will grow a new tail
and the tail section will grow a new head.
c. This way, a planarian that is damaged or cut into several pieces may grow
into many new organisms.
d. Examples of organisms that reproduce via rejuvenation are planarian,
dugesia (flatworm), starfish, lizard tail.
7. Budding:
a. Involves protoplasmic outgrowth containing a nucleus projecting
from the side of the parent cell.
b. The outgrowth will develop and grow to form a new bud.
c. Examples of organisms that undergo budding are hydra, tapeworm
and yeast.
8. Spore formation (sporation):
a. Mature spore are black in colour and produced and stored in the
sporangium.
b. Spores will released when the sporangium bursts. The tiny and
lightweight spores are blown by wind to other places.
c. When a spore is transported to a place with favourable growing
conditions, it will germinate to form new growths.
d. Examples of organisms that perform spore formation are Rhizopus
(bread mould), mosses, mushrooms and ferns.
9. Vegetative reproduction:
a. New plants are produced from existing plant organs or parts of
organisms.
b. The new plants have the same genetic makeup as the original plant.
c. Flowering plants can carry out vegetative reproduction.
d. There are several types of vegetative reproduction:
i. Rhizomes (ginger, lalang, asparagus)
ii. Tubers (potatoes)
iii. Bulbs (onion)
iv. Corms (yam, gladiokus)
v. Runners (strawberries)
vi. Suckers (banana)
e. Examples of plants that carry out vegetative reproduction are:
i. galangal
ii. sweet potatoes
iii. strawberries
iv. ginger
v. potatoes
vi. shallots

THE MALE REPRODUCTIVE SYSTEM

                                              Seminiferous Tubules

                                                   Straight Tubules

                                                        Rete Testis

                                                   Efferent Ductules

                                                       Epididymis

                                                      Vas Deferens

                                                           Urethra

1. The testes are each hung outside the body in a sac called the scrotum. 

2. The function of the testes is to produce the male gametes or sperms. 

3. The testes are located outside the body in the scrotum because sperms cannot 

form at human body temperature. 

4. The sperms move out from the testes in the sperm ducts. 

5. The prostate gland produces a milky fluid that protects the sperms.

6. The mixture of sperms and the secretion of the prostate gland is called 

semen. 

7. The urethra is a tube that allows sperm to move from the sperm duct to the 

penis. The urethra is also the tube that allows urine stored in the urinary 

bladder to flow out of the body. 

8. The function of the penis is to transfer sperms into the female reproductive 

organ.

ORGANS OF THE MALE REPRODUCTIVE SYSTEM – THE STRUCTURES AND FUNCTIONS

THE ROLE OF SPERM IN REPRODUCTION

1. A sperm is a male sex cell.
2. A sperm measures about 0.06 mm which makes it’s the smallest cell in a man’s
body.
3. It cannot be seen by naked eye. Under a microscope, sperm look like tadpoles.
4. A sperm cell is need to fertilise a woman’s egg (called the ova) to produce an
offspring.
5. A sperm is made up of three parts:
i. the head – contains genetic material (nucleus)
ii. midpiece – is the motor of the sperm (middle region)
iii. tail – enables the sperm to move.
6. Sperm production needs a temperature which is 3 to 5 degrees below body
temperature. The scrotum keeps the sperm at the correct temperature. If it
becomes too cool on the outside, the scrotum will bring the testicles closer to
the body for warmth.

THE FEMALE REPRODUCTIVE SYSTEM

1. The sexual organs of the human female reproductive system are the ovaries,
the fallopian tubes, the uterus and the vagina.
2. The function of the ovaries is to produce egg cells or ova.
3. An ovum is released by either of the ovaries about every 28 days.
4. The ovum moves out from the ovary into the fallopian tube or oviduct.
5. The fallopian tubes connect the ovaries to the uterus. The uterus is also known
as the womb.
6. The uterus is the place where the foetus develops during pregnancy. It has a
thick wall which is supplied with many blood vessels.
7. The wall of the uterus is the place where an embryo is implanted. The
development of embryo is completed in the uterus.
8. The cervix is the neck of the uterus. The wall of the cervix secretes cervical
mucus to protect the reproductive parts against bacteria infection. The cervix
opens into the vagina.
9. The function of the vagina is to receive sperms. It also serves as birth canal
during childbirth through which the baby comes out of the mother’s body.

THE ROLE OF AN OVUM IN REPRODUCTION

1. A normal woman has a pair of ovaries in her abdominal region.
2. The ovaries are able to produce female gametes called the ova.
3. An ovum is spherical structure surrounded by a layer of jelly coating. It
consists of a nucleus filled with chromosomes and cytoplasm containing stored
food.
4. An ovum is larger than a sperm, with a diameter of about 0.1 mm. Unlike the
sperm, it cannot move by itself.
5. Only one ovum is released from the ovary during a particular period of time.
6. Ovum will be released from the ovary of a woman who has reached puberty at
about 12 years old. The ovaries will stop producing ova when a woman is about
55 years old or when she reaches menopause.
7. The ovum is the largest cell in the female body because it contains dense
cytoplasm to provide food to the embryo at the early stage of its
development.
8. An ovum that is not fertilised by a sperm can only survive for 36 hours in the
human uterus. After this period, the ovum will die and is discharged from the human body.

Compare and contrast male and female gametes

THE MENSTRUAL CIRCLE

1. A woman’s ovary release ovum according to a particular period of time known
as the menstrual cycle.
2. The menstrual cycle is the regular monthly cycle involving ovulation and
menstruation. The duration of the menstrual cycle is about 28 days.
3. Ovulation is the release of a mature ovum from an ovary.
4. Menstruation is the discharge from the vagina when the ovum fails to be
fertilised by a sperm.
5. Menstruation occurs when the uterus lining breaks down. Hence, the broken
lining of uterus wall, dead ovum and blood will be discharged from the body.
6. The charges that take place throughout the menstrual cycle are controlled by
two types of sex hormones, namely oestrogen and progesterone.
7. Some women will experience premenstrual syndrome (PMS) for a few days
before the onset of the menstruation. The symptoms of this are anxiety,
nervousness, headaches, mood swings and tiredness.

FERTILISATION AND PREGNANCY

A. Formation of zygote

1. During the sexual intercourse 300 to 500 millions of sperms are deposited by
the penis into the vagina.
2. All of the sperms deposited in the vagina, only a few hundred arrived in the
fallopian tube. Most sperms have been destroyed by the acidic fluids secreted
by the vagina.
3. However some sperm survive because of the neutralising effect of the semen.
4. The surviving sperms swim up the vagina, through the cervix into the uterus
and finally reach the fallopian tube.
5. In the fallopian tube, only sperm will succeed in fusing with an ovum.
6. Fertilisation is said to take place when the nucleus of the sperm combines with
the nucleus of the ovum.
7. When the nucleus of the sperm penetrates the ovum, the tail of the sperm will
drop off and is left outside the ovum.
8. As soon as a sperm penetrates an ovum, a fertilisation membrane is formed outside the ovum to prevent other sperms from entering the ovum.

9. The product of fertilisation of the nuclei of both gametes is a zygote. Zygote
is the ovum which is fertilised. At this stage, a woman is said to be pregnant.
10. The period of development from fertilised egg to birth is known as pregnancy.
(at least 38 – 39 weeks)
11. After fertilisation, the zygote divides itself numerous times to form 2 cells, 4
cells, 8 cells and so on.
12. Then, the zygote moves along the fallopian tube to the uterus. The movement
of the zygote is caused by the push force of the cilia in the fallopian tube.
13. The zygote takes place about 7 days to reach the uterus.

B. Implantation of zygote

1. After about 7 days, the zygote attaches itself to the wall of the uterus, which
has been thickening in preparation to receive a zygote.
2. Attachment of the zygote to the lining of the uterus is called implantation.
3. If the implantation is strong, the zygote will develop into baby in about 9
months. If the implantation is not strong, the embryo will be discarded from
the mother’s body. This condition is known as miscarriage.

C. Development of embryo

1. After the zygote attaches into the wall of the uterus, it is known as an
embryo.
2. Following the process of implantation, a structure known as placenta is formed.
The placenta joins the embryo to the mother’s body via a special tube called
the umbilical cord.
3. The functions of placenta:
ii. attaching the embryo to the wall of the mother’s uterus.
iii. Transporting and directing antibodies and hormones from the mother’s
body to the foetus.
iv. Transporting nutrients (amino acid, vitamins, oxygen, fatty acid, glycerol
and glucose) in the mother’s blood to the foetus.
v. Acting as excretory organ to the foetus, that is excretory matters such as urea and carbon dioxide are excreted via the mother’s blood.

D. Development of foetus

PRENATAL CARE

1. Prenatal care is important for a pregnant woman to ensure that both the
expectant mother and the foetus are healthy.
2. A pregnant woman should take nutritious food for her own needs as well as for
the growth and development of the foetus.
3. Apart from nutrients and oxygen, other substances, circulating in the expectant
mother’s blood such as alcohol, chemical in tobacco smoke and drugs can also pass
through the placenta and be absorbed by the foetus.
4. Alcohol and chemical in tobacco smoke can cause a miscarriage and birth defects
such as mental retardation.
5. Drug can cause brain damage or even kill the foetus.

THE IMPORTANCE OF RESEARCH IN HUMAN 
REPRODUCTION

A. Sterility and ways to overcome sterility

1. Sterility is the inability to reproduce.
2. A man may be sterile because his testes do not produce enough sperms, or his
sperms may not be able to reach an ovum in the fallopian tube.
3. A woman may be sterile because she fails to ovulate or there is a blockage in
her fallopian tube, preventing the ovum and sperm from fusing.
4. Taking nutritious food which is rich in vitamins E and minerals may help to
overcome the problem of sterility.
5. Hormone treatment is used to increased sperm or egg production.
6. Surgery is used to correct problems such as blocked fallopian tubes or blocked
sperm ducts.
7. In Vitro Fertilisation (IVF) can be used to help infertile couples conceive. In
IVF, the eggs are mixed with sperms in culture dishes. Fertilisation occurs in
the culture dishes. The culture dishes are incubated for a several days for the
fertilised eggs to develop. The embryo is then inserted into the woman’s
uterus where implantation takes place.

B. Birth control or contraception

1. the birth control methods prevents ovulation, fertilisation and implantation of
fertilised ovum.
2. preventing ovulation:
a. contraceptive pills contain the sex hormones of the women which prevent
ovulation by changing the states in ovary.
3. preventing fertilisation:
a. natural method - which also called the rhythm method does not use any
contraceptive devices. Married couples avoid copulation during the fertile
period.
b. Condom – is a thin rubber sheath worn over the penis to prevent sperm from
entering the uterus during ejaculation.
c. Diaphragm – is a tin rubber cap fitted at the cervix of the woman to prevent
sperm from entering the uterus.
4. preventing implantation of the fertilised ovum:
a. intrauterine contraceptive device (IUCD) is inserted into the uterus to
prevent the fertilised ovum from implanting in the uterine wall and prevent
sperm from entering the uterus.
5. sterilisation is a permanent contraceptive method.
6. Ligation (tubectomy) – the cutting and tying of both the fallopian tubes of the
woman so that the ovum cannot be fertilised by any sperm.

THE SEXUAL REPRODUCTIVE SYSTEM OF FLOWERING 
PLANTS.

A. the different parts of a flower.

1. The parts and function of a flower are as follows:
 i. sepal - protects the flower at the bud stage.
 ii. petals - attracts insects for pollination.
 iii. stamen - the male reproductive organ.
 iv. filament - holds the anther
 v. anther - produces pollen
 vi. pollen grains - contain male gametes/male reproductive cell.
 vii. pistil - the female reproductive organ
 viii. stigma - receives pollen grains
 x. ovary - produces ovules
 ix. ovule - contains the female gamete/female reproductive cell.

B.. The functions of the male and female reproductive parts of a flower in sexual reproduction. 

1. The stamen and the pistil are the most important parts of a flower because
they produce the gametes for sexual reproduction.
2. The function of the anther of a stamen is produce pollen grains.
3. The pollen grains contain male gametes.
4. The function of filament is
b. to hold the anther to a position so that pollen grains can be released
effectively
c. to supplies the anther with nutrients and water
5. The stigma serves as a receptive surface for pollen grains. It has a sticky
surface so as to enable pollen grains to stick to it more easily.
6. The ovary produces ovules. The ovules contain egg cells or female gametes.

POLLINATION

A. What is pollination?

1. The transfer of pollen grains from the anther to the stigma is known as
pollination.
2. The plant resulting from cross-pollination is of better quality than the plant
germinated from a seed from self-pollination, inherits the good
characteristics of both parent plants compared with the plant from selfpollination which only possesses the qualities of only one parent plant.

B. Agents of pollination

1. Several types of pollinating agents such as water, wind or animal.
2. Aquatic plants like Hydrilla release pollen grains into the water to be floated
to the stigma of another flower.
3. Plant that are pollinated by wind have an elongated style which hangs out of
the petals and is light.

Table below show the pollination by wind and insects.

C. Type of pollination

1. The process of pollination takes place in two ways: 

a. self-pollination 

pollen grains are transferred from one anther to the stigma of the same 

flower or another flower of the same plant.

b. cross-pollination 

pollen grains are transferred from one anther to the stigma of the same 

flower or another flower of the same species.(different plant)

D..The Advantages of cross pollination

1.. Characteristics of a plant from a seed of cross-pollination are:

a. short ripening period 

b. more resistant against disease and pest attacks 

c. quantity of fruit increases
d. quality of plant is better.E. The use of cross pollination in agriculture.

THE DEVELOPMENT OF FRUITS AND SEEDS IN PLANTS

A. Fertilisation in plants

1. When a pollen grain lands on the stigma, it germinates and grows a pollen tube 

as shown below.

2. The germination of the pollen grain is stimulated by the sugary, sticky 

secretion on the surface of the stigma. 

3. The pollen tube grows through the length of the style to reach the ovary. 

4. The male gametes move down the pollen tube towards the ovary as shown 

below.

5. When the male gametes have reached the end of the pollen tube, a male 

gamete enters the ovule and fertilises the egg as shown below.
6. A zygote is formed in the ovule.

B. The formation of fruits and seeds

1. After fertilisation, the ovary develops into a fruit. 

2. The zygote in the ovule develops into an embryo and the ovule becomes a seed 

as shown below.

3. The fruit protects the seed during its development.

4. The other parts of the flowers, such as the petals, sepals, stigma and stamen 

will degenerate and drop off.

GERMINATION OF SEEDS

1. A seed consists of the embryo and a seed coat or testa as shown below.

2. The testa has a small hole called the micropyle. 

3. The testa protects the seed. 

4. The micropyle enables water and air ti enter the seed. 

5. The hilum is the part of the seed that attaches the seed to the fruit. 

6. The embryo is made up of the plumule, radicle and cotyledon. 

7. The embryo will develop into a seedling during germination. 

8. The plumule is the part of the embryo that will develop into a shoot while the 

radicle will become a root. 

9. The cotyledons of a dicotyledonus seed store food for use during germination. 

10. In a monocotyledonous seed, food is stored in the endosperm.

B. The physical changes of a seed during germination

1. Germination is the growth of the embryo in a seed to become a seedling. 

2. Once a seed germinates, many physical changes can be seen as shown below.

3. First, the testa breaks. The radicle is the first part of the seedling to emerge 

from the testa. 

4. The radicle grows downwards into the soil and lateral roots grow from it. 

5. The plumule emerges from the cotyledons. 

6. The shoot is bent to protect the plumule from damage. 

7. The plumule grows upwards to form two leaves. 

8. The cotyledons shrink and drop off as the food stored in them are used up. 

9. The seedling is now able to make its own food by photosynthesis.

C. The condition needed for germination

1. Germination of seeds will only take place if there is sufficient 

a. water, 

b. air and 

c. suitable temperature.

APPLICATION OF VEGETATIVE REPRODUCTION IN 

FLOWERING PLANTS.

A. Vegetative reproduction

1. New plants grow from the vegetative parts of the parent plants, such as the 

roots, stems or leaves. 

2. Flowering plants that reproduce vegetatively can be classified into three 

groups.

i. Plants that reproduce vegetatively by using their 

roots. 

1. These plants have roots that store food.

2. When the roots are detached from the parent plants, the roots can 

grow into new plants.

ii. Plants that reproduce vegetatively by using their 

leaves. 

1. These plants have leaves that produce buds. 

2. The buds can grow into new plants when the leaves are detached 

from the parent plant.

iii. Plants that reproduce vegetatively by using their stem. 

1. These plants have modified stems that produce buds.

2. The buds on the stems can grow into new plants. 

3. The modified stems are given special names such as runners, rhizomes, tuber and 

bulbs.

B. The application of research on vegetative reproduction in 

agriculture. 

1. Plant tissue culture

Refers to the cultivation of plant tissues in a nutrient medium in the 

laboratory to produce new plants.

2. Stem cutting

Another way to artificially propagate plants. In stem cutting, a new plant is 

produce by cutting off a portion of the stem of another plant. The cutting 

grows root and becomes a new plant.

THE END……good luck 

Perkumuhan Manusia ( Bab 3 Tingkatan 3 )

Perkumuhan Manusia

Apabila tindak balas kimia berlaku didalam sel-sel, bahan buangan (waste material) dihasilkan.

Bahan buangan ini adalah tidak berguna serta boleh bertukar menjadi toksik (toxic) jika terkumpul di dalam sel-sel badan.

Oleh itu, bahan-bahan buangan mesti dikeluarkan daripada badan untuk memastikan kesihatan yang baik bagi organisma.

Proses menghapuskan bahan buangan daripada badan dikenali sebagai perkumuhan.

Dengan kata lain, perkumuhan (excretion) adalah proses di mana organisma menyingkirkan bahan-bahan buangan daripada badannya.

Sistem perkumuhan manusia (human excretion system) terdiri daripada:

1. Sistem penghadaman (digestive system) untuk menyingkirkan air dan makanan yang terhadam melalui usus besar (intestine).
   
   
2. Sistem pernafasan (respiratory system) untuk menyingkirkan karbon dioksida dan air dengan gabungan sistem peredaran darah (circulatory system).
   
   
3. Sistem urinari / kencing (urinary system) untuk menyingkirkan air yang berlebihan, bahan buangan metabolik dan garam.

Organ perkumuhan manusia

Organ perkumuhan melaksanakan perkumuhan di dalam badan kita.

Manusia mempunyai tiga jenis organ perkumuhan, iaitu kulit (skin), paru-paru(lung) dan buah pinggang (kidney).

Bahan buangan dikeluarkan melalui organ perkumuhan dikenali sebagai bahan perkumuhan / kumuh (excretory materials).

Organ perkumuhan manusia.

Bahan perkumuhan manusia

1. Air, yang merupakan produk respirasi sel dan lebihan air yang diserap daripada makanan di dalam usus besar (large intestine).
   
   
2. Karbon dioksida, yang merupakan bahan buangan daripada proses respirasi sel.
   
   
3. Garam mineral seperti garam/natrium klorida (sodium chloride) yang berlebihan dalam makanan.
   
   
4. Urea, yang merupakan bahan bernitrogen yang dihasilkan daripada penguraian lebihan protein di dalam hati (liver).

Jadual di bawah menunjukkan tentang bahan perkumuhan yang dikeluarkan oleh organ perkumuhan manusia.

Organ perkumuhan	Bahan perkumuhan				Kaedah perkumuhan
	Air	Urea	Garam mineral	Karbon dioksida
Kulit	/	/	/	X	Menghasilkan peluh
Paru-paru	/	X	X	/	Melepaskan wap air
Buah pinggang	/	/	/	X	Menghasilkan urin

Kepentingan perkumuhan

1. Untuk mengekalkan kesihatan. Hasil perkumuhan seperti urea boleh meracuni sel hidup jika dibiarkan terkumpul di dalam badan.
   
   
2. Untuk mengawal kepekatan darah. Kepekatan garam yang tinggi di dalam badan, boleh meningkatkan kepekatan darah.
   
   
3. Untuk mengawal suhu badan. Penyejatan peluh pada kulit boleh menyejukkan badan.

THE END……good luck